The class of polymers of carbon monoxide and olefin(s) is well known in the art. Brubaker, U.S. Pat. No. 2,495,286, produced such polymers of relatively low carbon monoxide content in the presence of free radical initiators, e.g., peroxy compounds. U.K. No. 1,081,304 discloses the production of similar polymers of higher carbon monoxide content in the presence of alkylphosphine complexes of palladium compounds as catalyst. Nozaki extended the process to produce linear alternating polymers in the presence of arylphosphine complexes of palladium moieties and certain inert solvents. See, for example, U.S. Pat. No. 3,694,412.
More recently, the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon, now becoming known as polyketones or polyketone polymers, has become of greater interest in part because of the greater availability of the polymers. The more recent general processes for the production of the polyketone polymers are illustrated by a number of published European Patent Applications including Nos. 121,965, 181,014, 213,671 and 257,663. The processes typically involve the use of a catalyst formed from a compound of palladium, cobalt or nickel, the anion of a strong non-hydrohalogenic acid and a bidentate ligand of phosphorus, arsenic or antimony. The resulting polymers are rather high molecular weight materials having established utility as premium thermoplastics. The polymers find usage in the production of shaped articles such as containers for food and drink which are produced by processing the polyketone polymers by procedures which are conventional for thermoplastics.
In a preferred modification of the process for the production of the linear alternating polymers, the catalyst composition is formed from a compound of palladium, the anion of a non-hydrohalogenic acid having a pKa below 6 and a bidentate ligand of phosphorus. These catalyst compositions are very active and provide good yields of polymer in reasonable reaction times. However, a disadvantage of the catalyst composition results from the bidentate ligand of phosphorus, i.e., a tetraaryl diphosphine, being highly sensitive to the presence of oxygen. When oxygen is present, the disphosphine ligand will oxidize to the diphosphine oxide and the catalyst composition will lose catalytic activity. Since only small amounts of diphosphine are present, even small amounts of oxygen can cause difficulty. The oxidation of the diphosphine ligand can be avoided, of course, by ensuring that oxygen does not enter the reaction zone. It would be of advantage, however, to provide a catalyst composition which exhibits acceptable activity and yet is not sensitive to the presence of small amounts of oxygen.